Using useCallback helps React Native apps avoid unnecessary function recreations on every render. This reduces CPU work and memory churn, which helps maintain smooth 60fps animations and interactions. Without it, frequent re-creation of functions can cause extra renders in child components, leading to dropped frames and higher battery use.
Use useCallback to memoize functions that you pass to child components or use in effects. Make sure to list all dependencies correctly to avoid stale closures or unnecessary recalculations. Avoid overusing it for functions that don't cause re-renders, as it adds slight overhead. Profiling with React DevTools helps identify which callbacks benefit most from memoization.
useCallback is part of React's core hooks and does not increase your app bundle size. It has no direct impact on startup time. However, by preventing unnecessary renders, it indirectly improves perceived startup and interaction speed by reducing CPU load during initial UI setup.
useCallback behaves the same on iOS and Android since it is a React hook. However, performance gains may vary slightly due to differences in JavaScript engine optimizations (JavaScriptCore on iOS, Hermes or V8 on Android). Profiling on both platforms is recommended to ensure smooth UI performance.
Neither Apple App Store nor Google Play Store has specific rules about useCallback. However, both stores require apps to be responsive and not crash. Using useCallback correctly helps meet these expectations by improving UI responsiveness and reducing jank, which contributes to better user experience and higher review scores.
If your screen is slow, it might be because functions are recreated on every render causing child components to re-render unnecessarily. Check if you are missing useCallback for functions passed as props or used in effects. Also verify dependency arrays to avoid infinite re-renders. Profiling with React DevTools can help identify these issues.